McAleenon v LCCC (NICA): No Duty to Set Lifetime H₂S Standards and a Discretionary, Rationality‑Reviewed Duty to Investigate Statutory Nuisance

Introduction

This Court of Appeal in Northern Ireland judgment, delivered by Keegan LCJ with Treacy LJ and Horner LJ, is the merits determination remitted by the UK Supreme Court in Re McAleenon [2024] UKSC 31. It provides an important appellate clarification in Northern Ireland on three interlocking themes in environmental public law:

• The scope and standard of review of a district council’s duty to investigate statutory nuisance complaints under section 64(b) of the Clean Neighbourhoods and Environment Act (Northern Ireland) 2011.
• Whether the Northern Ireland Environment Agency (NIEA) and the Department/Minister (DAERA) are legally obliged to adopt or promulgate a lifetime exposure threshold for hydrogen sulphide (H₂S) (e.g., the 1 ppb/2 µg/m³ value discussed in England after the Walley’s Quarry dispute).
• The threshold and content of Article 8 ECHR duties in odour/pollution cases: what due diligence requires of regulators, and the limits of judicial intervention in setting technical standards.

The appellant, Ms Noeleen McAleenon, brought judicial review challenging alleged public authority failures to abate odour and pollution from the Mullaghglass landfill, operated by Alpha Resource Management Ltd (notice party). At first instance, Humphreys J dismissed the claim. The Court of Appeal initially disposed of the case on alternative remedy grounds, but the UK Supreme Court reinstated the judicial review, directing that the claim be determined by conventional public law standards without oral evidence. On remittal, the Court of Appeal addresses the merits and dismisses the appeal.

Summary of the Judgment

• LCCC’s investigation duty (s64(b) 2011 Act): The duty “to take such steps as are reasonably practicable to investigate the complaint” confers a discretion on the council as to how to investigate. The court’s review is on rationality (Wednesbury) grounds. LCCC’s collaborative approach (meetings, monitoring, odour diaries, liaison with NIEA/BCC/PHA) satisfied the duty. An internal misstatement that NIEA had “primary responsibility” was a legal error but immaterial: the council did not abdicate its function and took reasonable steps.
• NIEA/DAERA and lifetime H₂S thresholds (2013 Regulations): There is no public law obligation to promulgate a specific lifetime ambient H₂S standard or to adopt the English (UKHSA) values. Regulators are to apply the 2013 Regulations (BAT, “no significant pollution”, review of permits) and keep matters under review. The English responses to Walley’s Quarry were site-specific and not enforceable ELVs in permits. NIEA acted rationally in relying on PHA advice and in not fixing a numeric long-term ambient standard for Mullaghglass.
• Article 8 ECHR: Assuming engagement and victim status, the claim fails. Applying Fadeyeva and Richards (CA), the court will not substitute its own technical policies; the test is whether regulators acted with due diligence and struck a fair balance. On the evidence (extensive monitoring, enforcement steps, liaison with PHA, diminishing complaints, site closure to black-bin waste), any interference was justified; no breach is made out.
• Outcome: Appeal dismissed; Humphreys J’s decision affirmed. No breach by LCCC, NIEA, or DAERA.

Context and Procedural Background

Complaints of “rotten-egg” odours (typical of H₂S) arose from early 2018. Ms McAleenon complained to LCCC in December 2019 and pursued pre-action correspondence in April 2021. Proceedings issued May 2021. Humphreys J dismissed the judicial review in May 2022. On appeal, NICA (2023) initially found alternative remedies sufficed (private prosecution; tort of nuisance). The UKSC (2024) held the appellant could choose judicial review and remitted the merits, emphasising that public law standards apply and no trial with cross-examination is needed. Since 2022 the site ceased accepting black-bin waste; NIEA inspects as a closed landfill. Substantiated odour complaints have fallen away, the last noted by NIEA being May 2023.

The Issues on Appeal

1. Whether LCCC breached its statutory duty to investigate under section 64(b) of the 2011 Act.
2. Whether NIEA/DAERA acted unlawfully by failing to identify a lifetime H₂S exposure level that posed a risk.
3. Whether the respondents breached the appellant’s Article 8 ECHR rights.

Detailed Analysis

A. Precedents and Authorities Cited, and Their Influence

• Marshall v Gotham [1954] AC 360; Jenkins v Allied Ironfounders [1970] 1 WLR 304; Edwards v NCB [1949] 1 KB 704: These cases elucidate “reasonably practicable” as a balancing test: not everything physically possible must be done; decision-makers weigh risk against the sacrifice (time, cost, trouble). The court adopted this to hold that section 64(b) confers investigative discretion on councils.
• R (Anne) v Test Valley BC [2002] Env LR 22: Judicial review of statutory nuisance decisions focuses on rationality of the investigation and its outcome. The Court applied this rationality lens to LCCC’s investigative steps.
• R v Carrick DC ex p Shelley [1996] Env LR 273: Distinguishes the separate duties of local authorities and environmental agencies; existence of a parallel regulator does not extinguish the council’s duty. NICA acknowledged the point but held LCCC did not abdicate, and coordination with NIEA was permissible.
• Tameside [1977] AC 1014: A public body must take reasonable steps to inform itself. The Court used this as the touchstone for assessing whether LCCC/NIEA/DAERA gathered sufficient information; it found they did (monitoring, odour assessments, expert liaison).
• A v SSHD [2021] UKSC 37; BF (Eritrea) [2021] UKSC 38: No general public law obligation to promulgate detailed policies; the “in accordance with the law” requirement tolerates some uncertainty provided safeguards against arbitrariness exist. NICA used this to reject the claimed duty to publish or adopt a numeric lifetime H₂S standard.
• Fadeyeva v Russia (2007) 45 EHRR 10: Article 8 environmental cases require a minimum level of severity and, crucially, the due diligence/fair balance analysis. Courts do not prescribe technical standards. NICA applied this to review regulators’ diligence.
• R (Richards) v Environment Agency [2022] EWCA Civ 26: The CA overturned a first-instance declaration that effectively mandated numeric outcomes and timetables for H₂S reduction, holding courts must not set regulatory standards or deadlines. NICA tracked this reasoning to reject the appellant’s Article 8 and standards-setting claims.
• Verein KlimaSeniorinnen Schweiz v Switzerland (2024) 79 EHRR 1: Emphasises investigative diligence and public access to environmental information, but in a climate policy context. NICA distinguished it: no analogous international obligations or emergency status exists regarding lifetime H₂S thresholds at landfill sites.
• Re Ryan Taylor [2022] NICA 21: On “victim” and “potential victim” status requiring a real risk supported by convincing evidence. NICA noted doubts but assumed engagement/victim status without deciding the point.
• Bromley LBC v GLC [1983] 1 AC 768; Plan B Earth [2020] PTSR 1446: Used by the appellant on materiality of legal error; the Court accepted an error in LCCC’s characterisation of NIEA’s role but found no material impact given the substantive steps LCCC took.
• Dolan [2020] EWCA Civ 1605: Caution about courts second-guessing public health expertise. NICA emphasised deference to the PHA advice in NI.
• JR123 [2025] 2 WLR 435: On appellate scrutiny where questions of general principle or proportionality arise. NICA nonetheless found, even on a merits-sensitive proportionality lens, that due diligence was satisfied.

B. Legal Reasoning

1) The section 64(b) 2011 Act duty: discretion and rationality

Section 64(b) obliges councils, upon complaint by a resident, “to take such steps as are reasonably practicable to investigate the complaint.” Drawing on Marshall, Jenkins, and Edwards, the Court held this language confers discretion as to means. It is not a “do everything possible” duty. The question for the court is supervisory: were the steps taken rational and within the range of reasonable responses?

Applying that standard, the Court found LCCC:

• Engaged with NIEA, BCC, Alpha, elected representatives, residents and PHA.
• Conducted odour monitoring (including 46 daily visits in Apr–Jun 2021), sent odour diaries, and reviewed expert materials.
• Participated in weekly NIEA-LCCC coordination and information sharing.

Although a senior LCCC officer erroneously stated NIEA had “primary responsibility”, the Court held the misstatement was immaterial: LCCC did not abdicate; it undertook its own actions and reasonably relied on NIEA’s parallel technical role where appropriate. Crucially, the appellant did not identify concrete further “reasonably practicable” investigative steps that LCCC ought to have taken but did not.

2) NIEA/DAERA: no duty to set a lifetime H₂S threshold

The appellant argued regulators had to engage with and adopt a lifetime ambient H₂S value (e.g., 1 ppb / 2 µg/m³), pointing to the English Walley’s Quarry experience. The Court rejected this for four reasons:

• Legal framework: The 2013 Regulations require permits that ensure BAT is applied, and “no significant pollution” occurs (reg 11), allow emission limit values (ELVs) where necessary (reg 12), and mandate periodic review (reg 17). But nothing compels publication of a numeric, universal ambient lifetime H₂S threshold. A v SSHD/BF confirm no general duty to promulgate detailed policy standards.
• Comparative evidence: No UK landfill permit (including Walley’s Quarry) contains an ambient H₂S ELV. UKHSA values informed a site-specific public health risk assessment; they were not regulatory ELVs. It would be “unfair and potentially unenforceable” to impose ambient H₂S levels as permit conditions, given background urban H₂S.
• Expert deference and practicality: NIEA reasonably relied on PHA advice that Walley’s guidance values were not contextually appropriate for Mullaghglass. The Court underscored institutional competence: technical standards-setting is not for the court; it is rational for NIEA to follow PHA and WHO-linked assessment tools, and to apply FIDOR and instrumental monitoring (e.g., Jerome units).
• Evidence of diligence: The record showed sustained regulation: inspections, odour and gas monitoring, remedial directions to the operator (including gas well infrastructure and operational controls), and formal oversight groups. Complaints attenuated markedly, and the site ceased accepting black-bin waste in late 2022.

Result: No breach of duty by NIEA/DAERA under the 2013 Regulations for not adopting a lifetime H₂S threshold. The statutory duties were fulfilled by the ongoing, evidence-based, and expert-informed regulatory response.

3) Article 8 ECHR: due diligence satisfied; no judicial standards-setting

The Court assumed (without deciding) that the Article 8 threshold/severity and victim status were met. It then applied the Fadeyeva/Richards framework: the question is whether authorities approached the problem with due diligence and struck a fair balance, not whether the court would choose different technical standards or timelines.

On that test, the Court held:

• Regulators’ actions were extensive, iterative, and responsive to data and public complaints.
• Transparency and engagement occurred (public briefings, inter-agency meetings), consistent with the procedural safeguards recognised in Strasbourg case law.
• KlimaSeniorinnen does not require courts to impose quantified environmental standards; it emphasises investigative adequacy and public access—both adequately present here, in a non-analogous context (no treaty-based, nationwide mitigation duty for H₂S).

The Court declined to entertain a late “historic illegality” argument and, in any event, observed that substantial steps predated proceedings.

C. Impact and Significance

1) For district councils (statutory nuisance)

• Discretion affirmed: Section 64(b)’s “reasonably practicable steps” confers investigatory discretion; challenges are reviewed for irrationality. Councils may (and often should) coordinate with NIEA and health agencies for technical matters while retaining their own statutory role.
• Materiality of legal errors: Mischaracterising another agency’s “primary responsibility” will not vitiate decisions if, in substance, the council conducted a rational, documented investigation. However, councils should avoid such misstatements and continue to demonstrate ownership of their statutory duty.
• Good practice signals: Maintain odour diaries, conduct documented site and perimeter assessments, meet regularly with regulators, and evidence consideration of expert/health advice.

2) For NIEA/DAERA and environmental regulators

• No general duty to promulgate numeric ambient H₂S thresholds: Absent legislation or binding guidance, regulators are not required to adopt lifetime exposure values (such as 1 ppb). Site-specific, evidence-led regulation, applying BAT and “no significant pollution,” suffices.
• Expert liaison matters: Courts will defer where regulators show cogent reliance on competent public health bodies (PHA), keep abreast of WHO/UKHSA information, and record why particular numeric thresholds are inappropriate in context.
• Regulation 17 review duty remains live: While no obligation to set numeric ELVs, regulators must keep permits under review and consider ELVs “when necessary” (e.g., if pollution significance changes or new environmental quality standards arise). Detailed reasons for not setting ELVs in ambient air are prudent.

3) For Article 8 environmental litigation

• Due diligence over directives: Courts will ask if regulators have done enough, not require them to achieve numeric targets by dates. Claimants should focus on demonstrated gaps in investigation, monitoring, or obvious regulatory steps that were irrationally omitted.
• Victim status evidence: Where emissions abate, complaints subside, or the claimant’s exposure diminishes (e.g., relocation, site closure), standing and ongoing victim status will be scrutinised.
• Transparency: Although not determinative here, authorities should publish accessible summaries of monitoring, methodologies, and conclusions; this shields decisions under the procedural strand of Article 8 highlighted in Strasbourg jurisprudence.

4) For operators

• BAT and permit compliance remain central: Documented odour management plans, gas extraction, and monitoring are crucial—both to regulatory compliance and to resisting statutory nuisance allegations.
• Statutory nuisance defence: While “best practicable means” may be a defence to an abatement notice offence (s65(12)), it does not negate the council’s duty to investigate; operators should cooperate and demonstrate continual improvement.

Complex Concepts Simplified

• “Reasonably practicable” (s64(b)): Not “everything possible.” Decision-makers weigh the risk against the burden of further steps. If the burden is grossly disproportionate to the risk reduction, the step may not be “reasonably practicable.”
• Wednesbury irrationality: A high threshold for quashing. The question is whether the decision falls outside the range of reasonable responses open to the decision-maker, given the information available.
• BAT (Best Available Techniques): Techniques which are effective, technically/economically viable, and offer a high level of environmental protection. Includes technology and operational methods, not just equipment.
• ELV (Emission Limit Value): A numeric cap on pollutant emissions, usually at the source. Ambient air concentrations (in the community) are different; UK landfill permits typically do not include ambient H₂S ELVs.
• FIDOR odour test: A practical rubric assessing odour impact by Frequency, Intensity, Duration, Offensiveness, and the sensitivity of the Location.
• Jerome monitor: A field instrument commonly used to measure H₂S concentrations in ambient air for screening purposes.
• Article 8 “due diligence” in environmental cases: Authorities must adequately investigate, weigh competing interests, and act proportionately. Courts do not set technical standards or timetables; they assess the adequacy and rationality of what regulators did.
• “Victim” status: To rely on the HRA, a claimant must be directly affected or at real risk. Historic exposure without current risk can undermine standing unless a continuing issue is shown.

Key Paragraph Cross‑References

• LCCC duty and standard of review: paras [44]–[60]
• NIEA/DAERA obligations under the 2013 Regulations: paras [61]–[84]
• Article 8 analysis (Fadeyeva, Richards, KlimaSeniorinnen): paras [85]–[105]
• Outcome: paras [106]–[108]

Conclusion

McAleenon [2025] NICA 44 consolidates and applies a coherent public law framework for environmental odour cases in Northern Ireland. It establishes that:

• District councils’ investigation duty under section 64(b) is a discretionary obligation to take “reasonably practicable” steps, reviewed on conventional rationality grounds. Coordinated working with NIEA/health authorities is appropriate; an erroneous internal view about “primary responsibility” will not invalidate decisions absent material impact.
• NIEA/DAERA are not legally required to promulgate an ambient lifetime H₂S threshold (such as 1 ppb) under the 2013 Regulations. Their duties are discharged by evidence-led regulation, BAT, and periodic permit reviews, informed by public health expertise; courts will not mandate numeric standards.
• Article 8 ECHR claims in this arena turn on regulatory due diligence and proportionality, not judicially imposed standards or timetables. Where regulators monitor, engage, enforce, and transparently liaise with health authorities, courts will not intervene to set technical thresholds.

The decision provides practical guidance to councils and regulators on documentary diligence and inter-agency coordination, and to litigants on what must be shown to succeed in environmental rights challenges. It will likely be cited for the propositions that numeric lifetime exposure standards cannot be judicially compelled in the absence of a clear legal mandate, and that section 64(b) investigations are reviewed with deference to reasonable, technically informed choices.